ABSTRACT (Project 4: Lantz, Boitano, Zhang) Inhalable dusts in the Southwest US, especially those found downwind of legacy mine tailings and smelters, can contain high levels of arsenic and other contaminants. It is well established that arsenic exposure occurring via ingestion can result in adverse health effects that prominently include lung disease. Around legacy mines, such as the Iron King Mine and Humboldt Smelter Superfund site, arsenic exposures can occur via inhalation of aerosolized dusts from the mine tailings or abandoned smelter. Our previous work with ingested arsenic has demonstrated that exposure can affect airway structure/function in vitro and in vivo. Collectively, data indicate that arsenic exposure compromises the barrier integrity of the airway epithelium by inducing an epithelial to mesenchymal transition (EMT). Such loss of airway epithelial barrier function can lead to reduced innate immunity, increased inflammation, increased exposure of underlying tissue to airway insults, increased airway infection and ultimately, lung disease. While inhalation of arsenic-containing dusts represents a more direct exposure on the airways, and thus, the potential for similar or exacerbated lung dysfunction, the consequences of such inhalation is not known. We will determine the impact of real world and synthetic arsenic-containing dust particulates on airway epithelial health and lung function. Our integrated approach uses high capacity in vitro toxicity evaluation to inform on dust particulates that will be used in well-established primary culture mechanistic in vitro and in vivo models of airway function. Our hypothesis is that arsenic exposure by inhalation leads to EMT that permanently reduces airway epithelial barrier function and increases the risk of airway/lung disease. These alterations are in part mediated through induction/modulation of NADPH oxidase (NOX) and dual oxidase (DUOX) activity leading to increased production of reactive oxygen species (ROS). We will test our hypotheses with the following three Specific Aims: Aim 1) Use integrative, dissection, and synergistic approaches to determine mining-associated dust toxicity on airway epithelial cells. Aim 2) Determine if exposure of mining dusts results in airway EMT. Aim 3) Determine if alteration in NOX/DUOX is necessary and sufficient to affect airway EMT following mining dust exposure. Successful completion of these studies will establish a mechanistic understanding of the contribution of arsenic (or other metals) in real world dusts (such as those found in mining communities) to lung disease